In recent years, fluoro rubbers are industrially used in broad fields centering on the automobile and machinery industries because they give rubber compositions which are excellent in terms of heat resistance, chemical resistance, and the like.
However, it may not be said that their mechanical characteristics are sufficient, and their application to fields where a high mechanical strength is required was limited.
On the contrary, Patent Document 1 proposes a combination of a fluoro rubber with an epichlorohydrin rubber; and Patent Document 2 discloses a fluoro rubber vulcanizable composition containing (A) a fluorine-containing elastomer copolymer composed of a vinylidene fluoride unit and at least one fluorine-containing monomer and containing iodine or bromine, the fluorine-containing elastomer copolymer having an intrinsic viscosity (mL/g) in the range of from 50 to 100, (B) an organic peroxide, (C) a co-crosslinking agent, and (D) specified carbon black.
In addition, Patent Document 3 discloses a fluorine-containing elastomer vulcanizable composition including (a) a vulcanizable fluorine-containing elastomer, (b) a polyol vulcanizing agent containing a polyol compound as a crosslinking agent, and (c) a specified aliphatic amine compound; Patent Document 4 discloses a heat-resistant fluoro rubber composition composed of (a) 100 parts by weight of a fluoro rubber, (b) from 1 to 30 parts by weight of a divalent metal compound (provided that zinc oxide is excluded), (c) from 0.05 to 100 parts by weight of zinc oxide, (d) from 0.05 to 10 parts by weight of a polyhydroxy compound, and (e) from 0.05 to 10 parts by weight of a crosslinking auxiliary agent; and Patent Document 5 discloses a vulcanizable fluoro rubber composition containing (a) a tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer containing an iodine atom and/or a bromine atom, (b) an organic peroxide having a purity of 95% or more, and (c) a co-crosslinking agent having a purity of 95% or more.
However, all of these proposals are concerned with improvements in composition materials, such as an improvement of fluoro rubber species, an improvement in a combination with other rubber or a compounding agent, and the like, and it was difficult to make both a high tensile strength and a high elongation at break compatible with each other.
Then, a more enhancement of mechanical characteristics by a new technique is demanded.